What Kind of Cables Should I Use in my Home Network? - dummies

What Kind of Cables Should I Use in my Home Network?

By Lawrence C. Miller

A key component in wired home networks is — wires! More correctly, cables. Twisted-pair Ethernet cable is the most common type of home network wiring used today (and for the foreseeable future). Twisted-pair Ethernet cables are used to connect:

  • DSL/cable routers or modems to computers

  • DSL/cable routers or modems to wireless access points

  • DSL/cable routers or modems to hubs or switches

  • Computers to hubs or switches

  • Computers to other computers

  • Other devices (such as network printers) to computers, hubs, or switches

What’s the difference between a wire and a cable? A wire is a single conductor (typically copper) that may be solid or stranded. Two or more insulated wires grouped together in a sleeve or jacket (typically plastic) form a cable. (If each wire is not insulated, then it is technically still a wire.)

When purchasing network cables, you will most likely need Cat5e (or Cat6), UTP straight-through Ethernet cables with RJ-45 connectors. (RJ stands for registered jack.)

Twisted pairs and RJ-45 connectors

Twisted-pair Ethernet cables consist of eight copper insulated wires in a plastic sleeve. Two wires are twisted together in a pair for a total of four pairs, and then the four pairs are twisted together to form the cable. The twists and pairs affect certain performance characteristics of the cable, such as crosstalk, attenuation, and electromagnetic interference (EMI).

Crosstalk occurs when an electrical signal transmitted over one wire negatively affects the electrical signal transmitted over another wire. Attenuation is the gradual loss of intensity of an electrical signal as it travels over the wire. EMI is noise (unwanted electrical signals) that is generated between the wires by the various electrical signals that are transmitted.

A clear plastic jack, known as an RJ-45 connector, is attached to both ends of the twisted-pair Ethernet cable. An RJ-45 connector looks very similar to a telephone jack (which is known as an RJ-11 connector).

Twisted-pair Ethernet cable with RJ-45 connectors.
Twisted-pair Ethernet cable with RJ-45 connectors.

Twisted-pair Ethernet cabling is commonly referred to as simply Ethernet, Cat5, or UTP cable. Technically, Ethernet is a wiring and signaling standard that covers many types of cabling technologies; Cat5 is one category of several available categories; and UTP is one of two possible types. However, these terms are commonly understood to refer to twisted-pair Ethernet cabling.

Categories of twisted-pair cables

There are several categories of twisted-pair cabling, but only three that are commonly used for Ethernet networks: Category 5 (Cat5), Category 5e (Cat5e, or Cat5 Enhanced), and Category 6 (Cat6). The performance characteristics of Cat5, Cat5e, and Cat6 are as follows:

  • Cat5: Supports speeds up to 100 Mbps at 100 MHz, with a maximum cable length of 328 feet (100 meters).

  • Cat 5e: Supports speeds up to 1,000 Mbps (or 1 Gbps) at 100 MHz, with a maximum cable length of 328 feet (100 meters).

  • Cat6: Supports speeds up to 1,000 Mbps (or 1 Gbps) at 250 MHz, with a maximum cable length of 295 feet (90 meters).

Unshielded versus shielded cables

Twisted-pair Ethernet cabling can also be unshielded (common) or shielded (not so common). Unshielded twisted-pair (UTP) cabling is used in both large enterprise networks and small home networks. It is relatively inexpensive and much more flexible than shielded twisted-pair (STP) cabling.

STP cabling is more expensive and less pliable than UTP cabling. It is used in industrial environments and other noisy environments that are prone to high electromagnetic interference (EMI). The individual pairs of wires in STP cables are wrapped in foil or other metal shielding, and an outer metal shielding may also cover the entire group of twisted pairs (beneath the outer sleeve).

Straight-through versus crossover cables

In most cases, you will use straight-through twisted-pair Ethernet cables to connect the devices on your network. Crossover cables are sometimes required to directly connect two computers together (if one of them has a network adapter that is more than a few years old), to connect very cheap (or old) network switches that do not have an uplink port, or to connect some types of specialized network devices.

The difference between a straight-through and crossover cable is subtle but important. Two of the four pairs in a crossover cable are attached to the RJ-45 connector in a different order than in a straight-through cable, such that the transmitting and receiving wires are reversed.

Length and color of networking cables

When choosing cables for your network, you also need to consider length and color:

  • Length: Twisted-pair Ethernet cables come in standard lengths such as 3, 5, 7, and 10 feet. Longer lengths are available, and you can also have custom cable lengths made. The distance between your various network devices and your network switch or router will determine the length you need. Don’t forget to include enough length to run cables along walls, under rugs, and around corners as necessary.

  • Color: Twisted-pair Ethernet cables come in all sorts of colors. This decision can be based purely on your individual tastes and preference. Blue is perhaps the most common, but you might also consider white, gray, or some other color that doesn’t clash with your walls and carpet. Finally, you may want to stick with a single color for all the cables on your network.